Compressor on Cart

[jamie_1930]

I'm wondering what, if any, restrictions exist on putting a compressor on your robot cart in order to precharge your pneumatics systems. Any help would be appreciated.

[samir13k]

weve had it for the last few years on our cart, not solely for charging a robot (or charging a robot at all)... There hasnt been a problem with it, It's been useful for blowing out metal shaving also

[NOV8R]

The only restrictions as I understand the rules is (1) it must get power from the robot (2) Conform to the pneumatics manual safety requirements.

[jamie_1930]

Originally Posted by NOV8R

The only restrictions as I understand the rules is (1) it must get power from the robot (2) Conform to the pneumatics manual safety requirements.

So what you're saying is we would have to use the battery from the robot? Or could we just have the same type of battery, but separate from the robot?

[samir13k]

we've had a car battery powering our cart... i'll check for this season, but in the past its been acceptable...

[MrForbes]

Read the rules carefully. As I understand it, if you are using compressed air in your robot with no onboard compressor, then you have to power the compressor with the robot (not only do you need to use the robot battery, but you also need to control it with the cRio and pressure switch, and add another pressure release valve).

If you have a compressor on your robot, but you want to use an external compressor to pre charge it instead of running the robot to do this, then you probably ought to ask in the Q&A if it's legal to do so. The rules seem to imply that all the stored energy must come from the robot battery.

If you want a compressor on your cart for other reasons, you can probably do whatever you want as long as it's safe.

[DonRotolo]

Offboard air compressors which supply compressed air for use on the robot are covered very specifically in the rules. Please read the manual.

[Racer26]

I never really understood the logic on this ruling from the GDC... We've built a cart with compressor to pre-charge the robot, and been told we couldn't use it before.

How does forcing me to use the robot battery change anything when I can simply charge my pneumatics and then change batteries.

If the offboard system still has the pressure switch in it, then it won't over-pressurize, so I don't see the issue.

[Alan Anderson]

Originally Posted by 1075guy

How does forcing me to use the robot battery change anything when I can simply charge my pneumatics and then change batteries.

If the offboard system still has the pressure switch in it, then it won't over-pressurize, so I don't see the issue.

Using the robot battery and onboard control system doesn't change anything. That's the point. You're required to follow all of the pneumatic and electrical rules in the manual. The special permission to have the compressor offboard doesn't give you liberty to violate any of the other rules.

The issue is that robot inspectors need to be able to verify that everything is good. They should not be tasked with inspecting non-robot equipment such as a separate source of compressed air.

[Racer26]

As long as the robot has the required 125psi relief valve on board, and the gauges to show the pressure, wouldn't it be enough to have the cart pressurize the robot and the inspector watch that it shuts off appropriately? This doesnt require an inspection of the cart, only that the intended precharge system for the robot follows the intent of the rules (which in my mind, is to prevent the pneumatics system from exceeding 120-125psi.)

I mean, in the past when we were told we couldn't use it, its not like they made us take the ability to pressurize from the cart away, they just asked us not to use it, because of the rule violation.

[billbo911]

Originally Posted by 1075guy

As long as the robot has the required 125psi relief valve on board, and the gauges to show the pressure, wouldn't it be enough to have the cart pressurize the robot and the inspector watch that it shuts off appropriately? This doesnt require an inspection of the cart, only that the intended precharge system for the robot follows the intent of the rules (which in my mind, is to prevent the pneumatics system from exceeding 120-125psi.)

I mean, in the past when we were told we couldn't use it, its not like they made us take the ability to pressurize from the cart away, they just asked us not to use it, because of the rule violation.

Setting up the cart to follow the rules to the letter is NOT a difficult thing to do. All that is needed to do it is a little planning:
1) One additional shut off valve on the robot with a nipple in it to connect the tubing from the compressor..
2) Easy access to the load side of the Spike feeding the compressor so that the connections can be made and removed simply.
3) A short pigtail connection from the limit switch so the signal into the cRio can easily be connected/disconnected.

The 125psi relief valve would stay on the compressor as the rules require and save a bit more weight.

All of these connections could actually be done through one modular connector with the exception of the pneumatic tubing.

[Al Skierkiewicz]

To repeat...
The off board compressor rules are to give teams the option of trading weight savings for reduced air usage. All things must be equal for either system, i.e. you have to use the robot battery, Crio, gauges, Spike, etc. and prove the the system pressure is under control of the robot as well as all safety rules are met. Those teams that choose to give up the weight of the compressor can move it off board but are limited to how much air they can use in a match. That is the quid pro quo for allowing one implementation or the other.


"<R75> Compressed air for the pneumatic system on the ROBOT must be provided by one and only one compressor. This compressor may be either the Thomas Industries compressor from the KOP, or an equivalent compressor that does not exceed any of the KOP compressor performance specifications (specifically: 12v, 0.8cfm flow rate, 120psi continuous pressure, 120psi maximum pressure compressor). Note: if an alternative compressor is used, during inspection the team may be required to provide documentation to show compliance with the performance specifications. Compressed air shall not come from any other source. The compressor may be mounted on the ROBOT, or it may be left off the ROBOT and used to pre-charge compressed air in the storage tanks prior to bringing the ROBOT onto the FIELD. Off-board compressors must be controlled and powered by the ROBOT.

The only difference between an on- and off-board compressor is that the off-board compressor is physically removed from the ROBOT. The intent of this rule is to permit teams to take advantage of the weight savings associated with keeping the compressor off-board. However, using the compressor off-board of the ROBOT does NOT permit non-compliance with any other applicable rules."

[Racer26]

Al, Bill, Alan, and everyone else:

I know what the rules are, and plan to build accordingly.

I just never understood why the rules are the way they are, when there exists several implementations different to the letter of the rules, which still IMO satisfy the intent (safety, and no more than 120psi at start of match) while giving no competitive advantage.

I suppose simplicity of inspecting the safety of the setup is a fair reason, but other than that, I see no good reason to disallow it.

[Al Skierkiewicz]

Originally Posted by 1075guy

I suppose simplicity of inspecting the safety of the setup is a fair reason, but other than that, I see no good reason to disallow it.

The method described above and the rules are to insure that teams with off board compressors follow the same test and system requirements as those teams with on board compressors. That last paragraph sums it all up. Nothing more. (It is more difficult to inspect an off board compressor.)